I thought it was pretty dumb and shallow, but some people liked it so ymmv.
So far issue 0 which has Shazam in the main feature and issue 15 today have been the best two issues of the series, so I'm hopeful Johns is getting his shit together.
Based on the solicits, the next issue of Justice League (#16) might be the last Shazam back up because #17 has no mention of it. The solicit for #17 talks about the expansion of the team and we have already been told that Shazam will be the first new member. Gary Frank is supposed to begin drawing Batman Earth One, Vol. 2 shortly, so his days working on Shazam are numbered.
Johns has been creating a rich world with Shazam and while I’d like to see him continue when it eventually goes to series, I don’t see how he will be able to continue to juggle Aquaman, Green Lantern, Justice League, JLA, co-writing Vibe, and 2013’s Trinity War event book. While I would love for Shazam to get his own book in the next wave, I have a feeling he will instead play a large role in Justice League and Trinity War. Maybe when Gary Frank has finished with Batman E1, he will reteam with Johns and launch Shazam! #1. Finally!
Guardian of Love
Overall, I've enjoyed it. I didn't mind them making Billy a little less noble and all, but like the origin JL arc, I feel Johns overexaggerated that, making the character seem like a giant dick more than anything (I get that he was jaded by the system, but I still thought the characterization was still way over-the-top). But still, I've liked it enough so far that I'm looking forward to seeing where it goes. And can't go wrong with Gary Frank's art.